To a mixture of methyl 3-[4-({4-[({4-[(Z)-2-(diethoxyphosphoryl)ethenyl]-1-phenyl-1H-pyrazol-3-yl}oxy)methyl]-2-methoxyphenoxy}methyl)-5-methyl-1,3-oxazol-2-yl]benzoate (1.38 g), tetrahydrofuran (10 mL) and methanol (10 mL) was added 1N aqueous sodium hydroxide solution (5 mL), and the mixture was stirred at 50° C. for 1 hr. To the reaction mixture were added 1N hydrochloric acid (5 mL) and water, and the mixture was extracted with ethyl acetate. The organic layer was washed with saturated brine, dried over anhydrous magnesium sulfate and concentrated to give 3-[4-({4-[({4-[(Z)-2-(diethoxyphosphoryl)ethenyl]-1-phenyl-1H-pyrazol-3-yl}oxy)methyl]-2-methoxyphenoxy}methyl)-5-methyl-1,3-oxazol-2-yl]benzoic acid as colorless crystals (1.26 g, yield 93%). Recrystallization from acetone-hexane gave colorless prism crystals. melting point: 158-159° C.
